What to know about bird flu in 2025, from how it's spread to symptoms and egg impacts
From worries about food safety to egg prices, Americans have questions about the bird flu.
This strain of bird flu, also known as H5N1, is not entirely new. It's been detected in a variety of bird populations since January 2022, and in March of last year, it was found in dairy cows for the first time. Since then, there have been nearly 70 human cases, mostly in dairy and poultry workers, including one fatality.
To help break down the latest, Dr. Céline Gounder, CBS News medical contributor and editor-at-large for public health at KFF Health News, shared what to know on "CBS Mornings Plus" Thursday.
How does bird flu spread? Can people get bird flu?
Bird flu can infect birds as well as mammals, including pigs, cattle and cats. People can also get infected when they come into close contact with infected animals, which is why farm workers are at high risk for infection.
"They work in the dairy industry. They have milk all over them because they're milking the cows. They're working with poultry. So when they come into close contact, like that, whether it's through breathing or contact with their hands, their eyes, etc., that's how they're getting it," Gounder said.
So far, the spread has only been from animal to human.
Health officials have said for months that while the spread of the virus in animals warrants stepping up precautions for workers dealing with sick cows and birds, the risk to the general public remains low.
Still, experts are worried about the virus mutating as it spreads, making new hybrid strains that could lead to human-to-human spread.
"Those hybrid strains can be especially dangerous to humans, and these are the strains that we worry could spark a pandemic," Gounder said.
Does bird flu affect eggs?
Bird flu continues to affect the availability and price of eggs as the disease hits farms and wipes out flocks.
Last year, bird flu killed more than 40 million egg-laying birds. Including ducks and chickens, 148 million birds have been ordered euthanized since H5N1 began spreading around the U.S. in 2022
When it comes to eggs and milk, Gounder said cooking and pasteurizing is the safest way forward.
"If you cook your food, your risk of getting infected with any number of things is reduced. It's much safer. You're less likely to get sick and die," she said. "Same thing with milk. We learned in the 1800s that pasteurizing, which means boiling your milk — you're not doing anything unnatural — also reduces your risk of any number of infectious diseases, including the bird flu."
Health experts have long warned against consuming unpasteurized dairy products like raw milk, which has become a recent influencer-promoted trend.
Bird flu symptoms
Bird flu has led to a wide variety of symptoms during recent outbreaks, including common flu symptoms like cough and vomiting. Many have also had conjunctivitis or pink eye as their only symptom, which experts suspect is from contaminated milk from cows infected by bird flu being splashed onto workers.
Most of the U.S. cases have seen their symptoms resolve a median of four days after first getting sick. The majority were also treated with the antiviral oseltamivir, also known by the brand name Tamiflu, which may have helped to speed their recovery.
Is there a cure for bird flu?
In addition to treatment options for those infected, there are potential options for prevention.
The seasonal flu vaccine is not designed to boost protection against H5N1, but there are different kinds of vaccines that health authorities have prepared for a potential bird flu pandemic.
Health authorities routinely test those pandemic vaccines against the bird flu virus to see if new strains have evolved to escape the protection from those shots.
"The strategic national stockpile has a limited number of bird flu vaccine doses. The problem is, those are not going to be a perfect match to what's circulating out there right now," Gounder said.
In addition, under the prior administration, the federal government planned to develop mRNA vaccines for this.
"The advantage of mRNA vaccines is they're much faster to produce, but those would need to go through clinical trials, FDA approval. People would actually need to take them," Gounder said. "Under what (Robert F. Kennedy, Jr.) has proposed (as Health and Human Services secretary), it would be much more difficult for the FDA to approve a vaccine. The bars would be set higher. He wants to put a pause on NIH research on infectious diseases for the next eight years, which would mean that the funding to develop vaccines and treatments for bird flu would be more limited."
